Bag machine

ABSTRACT

The bag machine of the present disclosure is of the type which can produce bags made of various thermoplastic sheet material and can be adapted to make side weld or bottom weld bags. The following description will, however, be confined to the production of side weld bags. A roll of plastic web is mounted on an unwind stand and traverses a folding board constraining the web to fold along its longitudinal median or along a line spaced from and parallel to the longitudinal median in the event it is desired to produce wicketed bags having a lip with a pair of holes in which is inserted a U-shaped wire called a wicket. Downstream of the folding board a gusseter is provided to produce a fold which permits greater expansion at the bottom of the bag. The folded and gusseted web thence comes under the influence of a reciprocating transversely disposed seal and cutter bar which divides the web, at longitudinally spaced intervals, to produce individual bags. The bags are then transported to a table which is provided with devices for arranging the bags into a stack.

United States Patent [151 3,678,812 Wech [45] July 25, 1972 BAG MACHINE Primary Examiner-Bernard Stickney 72 inventor: Robert J. Wech, Pinecrest Road RR. 5, Anders et Green Bay, WIS. 54303 [57] ABSTRACT [22] Filed: Sept 1971 The bag machine of the present disclosure is of the type which 21] A N 176,900 can produce bags made of various thermoplastic sheet materi- Related U.S. Application Data Division of Ser. No. 760,048, Sept. 16, 1968.

References Cited UNITED STATES PATENTS 6/1965 Ramaika ..270/86 8/1966 Ramsey ....270/86 al and can be adapted to make side weld or bottom weld bags. The following description will, however, be confined to the production of side weld bags.

A roll of plastic web is mounted on an unwind stand and traverses a folding board constraining the web to fold along its longitudinal median or along a line spaced from and parallel to the longitudinal median in the event it is desired to produce wicketed bags having a lip with a pair of holes in which is inserted a U-shaped wire called a wicket. Downstream of the folding board a gusseter is provided to produce a fold which permits greater expansion at the bottom of the bag. The folded and gusseted web thence comes under the influence of a reciprocating transversely disposed seal and cutter bar which divides the web, at longitudinally spaced intervals, to produce individual bags. The bags are then transported to a table which is provided with devices for arranging the bags into a stack.

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saw u 0F 4 INVENTOR- ROERT J. "EC" By 6 60 Mm ATTORNEYS BAG MACHINE BACKGROUND OF THE INVENTION In order to attain a production rate of 200 or more quality thermoplastic bags per minute it is essential to design the bag making machine with features that provide: (a) positive control of the film during its unwinding from the parent roll; (b) maintenance of a fixed positional relationship between the parent roll supporting stand and the infeed frame of the bagging machine; when desired, a gusseting mechanism which provides a minimum drag to the film while insuring a gusset of constant depth; (d) web draw rolls whose nip pressure is evenly distributed and has the ability to apply a differential nip pressure from one end of the rolls to the other; (e) mechanism which will release the nip pressure in the event film movement is stopped to prevent the creation of flat spots on the film; (f) a seal bar which will maintain a uniform evenly distributed temperature throughout its length and one that is shielded to prevent heat loss to the film; (g) a seal bar drive arranged for a manual or automatic lift when desired or when web feeding is interrupted for any reason; (h) mechanisms to vary the length of the bag being produced while the machine is operating to correct or change the size of the bags accurately under operating conditions with no down time and; (i) a bag transporting conveyor, which conventionally runs at higher speed than the film, including an easily adjustable positive control arrangement whereby adjustments can be made under operating conditions to insure that the trailing end of the bag is engaged by a conventional bag slow down mechanism to stack the bags so that their margins are in registration.

SUMMARY OF THE INVENTION Therefore in accordance with one feature of the present invention a web or film unwind stand is provided with the ability to maintain a fixed relationship with the infeed frame of the bag machine for purposes of insuring accurate alignment of the stand with the bag machine. Such a condition is necessary to insure proper tracking of the film through the bag machine and to prevent the creation of wrinkles in the web. In making side weld bags the unwind stand is supplied with a roll of film whose width determines the depth of the bag to be produced. It is conventional practice to train the web over a V-shaped folding board, hereinafter sometimes referred to as a V-board or folding board, which constrains the web to fold upon itself before being received by drive rolls mounted on the infeed frame of the bag machine. As will be made evident the unwind stand must be positioned so that the axis of the parent roll of stock is exactly or substantially exactly parallel to the longitudinal median of the bag machine. Stated another way the longitudinal median of the film must unwind so that it defines an angle of 90 to the path the folded film takes through the bag machine. In achieving this objective the present invention provides a very rigid locating frame connected to the infeed frame of the bag machine. The locating frame is provided with a member establishing a guideway or rail which is engaged by roller guides carried by the V-board and the base frame of the unwind stand. Such construction allows movement of the unwind stand normal to the longitudinal median of the bag machine and thus insures that the above described relationship is maintained irrespective of the width of the film or whether the machine is used as a double lane machine.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. IA and 18, when viewed together along the break line R show the bag machine of the present invention in longitudinal section wherein the path of the web is shown by a broken line and the direction of web feed is indicated by arrows applied thereto,

FIGS. 2A and 2B, considered together along the break line S, illustrates the bag machine in plan view,

FIG. 3 is a partial perspective of the unwind stand on reduced scale showing its connection to the infeed frame of the bag machine,

FIG. 4 is a section taken substantially along the line 4-4 of FIG. 2A showing a front elevation of the unwind stand on reduced scale, and of a simplified character, further illustrating the unwind stand guiding system.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Arrangement With reference to FIGS. IA, 18, 2A and 2B it will be noted that the bag machine of the present invention is generally indicated by the numeral 20 and it comprises an unwind stand 22 (FIG. 2A) rotatably supporting core shafts 24 which in turn support film rolls 26. The web, designated by the letter W, unwound from the roll 26 is folded along a line parallel to its ends by a folding board or a V-board 28. When so called even edged bags are made the fold line is located at the longitudinal median of the web while the fold line for lipped bags is spaced from and parallel to the longitudinal median. FIG. 2A shows the V-board set up for producing lipped bags since the left hand margin of the web, identified by L.H., is laterally spaced from the right hand margin R.H. downstream from the V- board 28. The web then comes under the influence of a gusseting mechanism 30 which forms an inwardly directed fold on that portion of the web which defines the bottom of the completed bag. The fold is shown by a dotted line in FIG. 2A and is identified by numeral 32.

Referring to FIG. IA it will be seen that the gusseting mechanism 30 is mounted on support arms 34 pivotally connected to a transverse rod 36 mounted to and extending between laterally spaced infeed frame members 38. Rotatably supported on the transverse rod 36 is a roller 40 which directs the web between a first set of infeed rolls of 42 connected to conventional nip pressure regulating means 43. The web is thence trained about a plurality of idler rollers 44, mounted on dancer arms 46, and rollers 48 extending between and rotatably mounted on the infeed frame members 38. The length of web accumulated in the path defined by the rollers 44 and 48 serves to provide a temporary supply which automatically increases or decreases in response to transient values of web tension. This arrangement tends to produce a constant value of web tension.

The bag machine frame comprises a base plate 50 having mounted thereon transversely spaced upwardly projecting side frame members 52 located substantially at the midportion of the machine. At the discharge end, outfeed frame members 54 are also mounted on the base plate 50 and served to support bag discharge control devices explained in detail hereinafter.

Referring again to FIG. IA it will be observed that between the infeed frame members 38 and the mid-frame members 52 a horizontal accessory platform 56 is connected therebetween and it serves to support hole punching assemblies 58 mounted on a base plate 60. As shown in FIG. 2B the base plate 60 is mounted on a rectangular frame 62 and is transversely adjustable on this frame. It is held in a selected transverse position by a lock screw 64. Longitudinal adjustment of the rectangular frame 62 carrying the hole punch assemblies 58 is accomplished by racks 66 and pinions 68. As shown diagrammatically in FIG. 2B the racks 66 are fixed to the inner surfaces of the side rails 56 while the pinions 68 are keyed to a transversely extending shaft 70 rotatably mounted in the rectangular frame 62. On one end of the shaft 70 a knob 71 is keyed for rotating the shaft 70 and consequently adjusting the longitudinal position of the hole punching assemblies 58.

Downstream of the hole punching assemblies 58 an electronic web registration device 72 commonly referred to as a scanner, is likewise mounted for longitudinal and transverse adjustment. Longitudinal adjustment is accomplished by pinions 74 (FIG. IA) in mesh with the racks 66. The pinions 74 are mounted on a transverse shaft 76 rotatably carried in generally L-shaped frames 78. On the upright legs of the L frames 78 a transverse bar 79 is secured. Slidably mounted on the bar 79 is a scanner 72 which can be locked in any transverse position by a lock screw 80. On the horizontal leg of the L frame 78 a transverse bar 82 is mounted and it will be observed, by inspection of FIG. 1A, that its upper surface is in substantially the same plane as the web line. In order to insure repeated response of the scanner the upper surface of the transverse bar 82 is white in color so as to provide good contrast for detection of the printed registration mark. As is conventional the scanner is electrically connected to the control circuit of the bag machine to deenergize the clutch and simultaneously energize the brake thereby arresting the movement of the web for a sufiicient period of time to allow the transverse seal bar to operate and thereby make the side weld for two longitudinally adjacent bags. After the seal bar completes its function the control circuit is then conditioned to release the brake and engage the clutch commencing web movement.

-As shown in FIG. 1B upstream of the scanner the web passes between intermittently operating draw rolls 84 associated with upper and lower sets of the stripper fingers 86 and 88, respectively, detachably mounted on transverse bars 90 and 91. The draw rolls are connected, as hereinafter will be more particularly described, with means, generally indicated by the numeral 92, for controlling the nip pressure the draw rolls exert on the film and for removing the nip pressure when required, either selectively or automatically.

To resist the deflection of the draw rolls, particularly at their mid portion and thereby insure an even value of nip pressure along the length of the draw rolls, a back-up roll 94, in rolling contact with the lower draw roll, is provided. The backup roll 94 is rotatably mounted in a yoke 96 having a link extension 98 which forms one link of a parallel linkage mechanism 100. The vertical position of the back-up roll 94 and accordingly the back-up, force it will apply to the draw rolls 84 can be selected by adjusting a screwjack 102.

Immediately downstream of the draw rolls there is provided a vertically reciprocating sealing mechanism 104,- cooperating with an intermittently rotating seal roll 106 for making the transverse seals in the folded web. These seals constitute the lateral margins of the bags. The seal mechanism is reciprocated by a pair of cams 108 (one of which is shown in FIG. 1B) keyed to a shaft I 10.

After the web passes the seal mechanism individual bags are at that time produced and they are received by a continuously operating belt conveyor 112. The index conveyor comprises a series of transversely spaced and aligned upper and lower sets of belts, 114 and 116 respectively, moving in a direction indicated by the arrows in FIG. 18. Those reaches of the belts which are traveling from left to right, as viewed in FIG. 1B, are

in contact for the purpose of gripping the bags dischargedv from the sealing mechanism and transporting them to a stacking table 118 provided with adjustable stop plates 120 for collecting the bags in a stack.

The upper belts 114 of the index conveyor 112 pass around an idler shaft 122 rotatably supported on linkages 124 mounting a cam follower roller 126 which is held in engagement with a cam 128 by a spring 130. As shown in FIG. 1B the cam 128 is mounted on a shaft 132 and during operation the linkages 124 are oscillated raising and lowering the idler shaft 122 which serves the purpose of accommodating any over travel of the bags as they issue from the sealing and cutting mechanism 104 and thus prevent wrinkling ofthe bag.

Before the bags are discharged to the stacking table 118 they come under the influence of conventional corrugating rollers 134 which serve to stiffen the bag in the direction of movement so as to prevent distortion thereof as it is ejected to the stacking table 118. Before being discharged to the stacking table the trailing end of the bag is momentarily gripped by a slow down mechanism 136 of known construc tron.

In order to synchronize the speed of the belt conveyor so that bags discharged therefrom are momentarily gripped at or adjacent their trailing edge. an electrically adjustable direct current drive arrangement 138 (FIG. 1B) is provided. The drive 138 includes a DC motor, belt and pulley, not shown, for driving a shaft 143. The shaft 143 has an adjustable pitch pulley I44 at its opposite end which drives a belt 145 trained about a pulley 146 mounted on a shaft 147. The shaft 147 provides power for the corrugating rollers [34. To drive the index conveyor 112, a belt and pulley drive train, not shown, transmits power from the shaft 143 to the upper index conveyor drive roller which is adjacent the lower set of corrugating rollers 134. For purposes of adjusting the pitch of the adjustable pulley 144, a tightener pulley 148 tensions the belt 145 and is carried by a stub shaft 150 mounted on an adjustable arm I52.

Unwind Stand FIGS. 2A, 3 and 4 show the novel unwind stand of the present invention which, as mentioned above, is structurally unified with the bag machine to insure proper tracking of the web regardless of its position along a line which is normal to the longitudinal median of the bag machine. Referring to FIGS. 3 and 4 it will be observed that the unwind stand comprises a platform 154, of generally rectangular configuration, rotatably mounting wheels 156 which allow the platform to be moved as desired. The platform has mounted on its upper surface a frame structure 157 having opposed side plates 158 interconnected by parallel, laterally extending, bars 160. Rollers 162, running in tracks 164, mount the frame structure 157 for lateral movement relative to the platform 154. Such movement is required to maintain one edge of the film fixed with respect to a reference point so that bags of consistent dimensions are produced. Such lateral movement on the frame structure 157 is efiected by a conventional edge guide, preferably of the pneumatic hydraulic type, which controls the extension and retraction of a hydraulic cylinder 166 connected, as shown in FIG. 3, to the platform 154 by a bracket 168 and to one of the side plates 158 by a clevis connection 170. The hydraulic cylinder is extended or retracted by the edge guide sensing control (not shown) so as to keep one margin of the film located in a predetermined position with respect to the platform 154.

The unwind stand 22 is joined to the bag machine so that it is allowed to move in a direction transverse to the longitudinal median of the bag machine and in a direction normal thereto thus serving to position the folded web transversely to the bag machine. This is particularly important where the bag machine is associated with two unwind stands which feed folded roll stock to the bag machine, which as a result, produces two bags each time the seal and cutter bar is reciprocated. To insure movement of the unwind stand in the mentioned normal direction, a guide rail 172 is rigidly connected to the infeed frame members 38 by structural members 174. On the platform there isrigidly connected a slotted block 176 rotatably carrying rollers 178 which are in rolling engagement with the opposed vertical surfaces of the guide rail 172. An A frame 180 connected to the platform 154 carries a roller 182 in rolling engagement with the upper surface of the guide rail 172. As shown on FIG. 2A the guide rail 172 extends a sufficient distance laterally of the bag machine to allow positioning of the unwind stand at any desired operating position.

While it is not shown, the platform 154 can be rolled by a crank mechanism to position the unwind stand as desired. Regardless of the transverse location of the unwind stand it will always maintain its normal relationship with the longitudinal axis of the bag machine by virtue of the guide rail 172 and the rollers 178 and 182 which constrain the unwind stand to maintain its desired attitude. To minimize construction cost, the rollers 178 and 182 can be replaced with guide pins slidable along the guide rail 172.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as set forth in the appended claims.

Iclaim:

1. A bag machine comprising means for supporting a supply roll of film to unwind about an axis which is parallel to the longitudinal median of such bag machine, a folding board for folding the film on or near its longitudinal median and for directing the folded film to follow a line parallel to the longitudinal median of the bag machine, said bag machine having an infeed frame adjacent said folding board, a guide frame interconnecting said film rol] supporting means and said infeed frame to maintain a relationship of 90 between the longitudinal median of the bag machine and the transverse center of the film roll, and means on said film roll supporting means and on said folding board in contact with said guide frame for constraining the film roll supporting means and the folding board to maintain the 90 relationship as they are adjusted transversely relative to the longitudinal median of the bag machine.

2. The apparatus according to claim 1 wherein said constraining means comprises rollers on said film roll supporting means and a roller on said folding board in rolling engagement with a guide rail, said rollers being disposed to roll along the upper and side surfaces of said guide rail.

3. An apparatus for maintaining a fixed relationship between a web roll supporting stand and the frame of a bag machine which produces bags from the web unwound from said roll, said web roll supporting stand mounts the web roll on a rotatable unwind shaft whose axis is parallel to the longitudinal median of said bag machine, the improvement comprising a rigid structure interconnecting the said supporting stand and said bag machine frame, means on said interconnecting frame defining a guide rail located normal to the longitudinal median of said bag making frame. and means, rigidly connected to said supporting stand and in rolling engagement with said guide rail at longitudinally spaced points for permitting movement ofsaid supporting stand therealong while maintaining its normal orientation relative to the bag machine. 

1. A bag machine comprising means for supporting a supply roll of film to unwind about an axis which is parallel to the longitudinal median of such bag machine, a folding board for folding the film on or near its longitudinal median and for directing the folded film to follow a line parallel to the longitudinal median of the bag machine, said bag machine having an infeed frame adjacent said folding board, a guide frame interconnecting said film roll supporting means and said infeed frame to maintain a relationship of 90* between the longitudinal median of the bag machine and the transverse center of the film roll, and means on said film roll supporting means and on said folding board in contact with said guide frame for constraining the film roll supporting means and the folding board to maintain the 90* relationship as they are adjusted transversely relative to the longitudinal median of the bag machine.
 2. The apparatus according to claim 1 wherein said constraining means comprises rollers on said film roll supporting means and a roller on said folding board in rolling engagement with a guide rail, said rollers being disposed to roll along the upper and side surfaces of said guide rail.
 3. An apparatus for maintaining a fixed relationship between a web roll supporting stand and the frame of a bag machine which produces bags from the web unwound from said roll, said web roll supporting stand mounts the web roll on a rotatable unwind shaft whose axis is parallel to the longitudinal median of said bag machine, the improvement comprising a rigid structure interconnecting the said supporting stand and said bag machine frame, means on said interconnecting frame defining a guide rail located normal to the longitudinal median of said bag making frame, and means, rigidly connected to said supporting stand and in rolling engagement with said guide rAil at longitudinally spaced points for permitting movement of said supporting stand therealong while maintaining its normal orientation relative to the bag machine. 